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HYPOGENIC CAVE FEATURES
isolated steeply ascending passages or clusters of rift-like
passages connecting to some master level, and prominent
outlet segments rising from the bulk of passages and rooms
(Figure 17). These structures are composed of network and
spongework mazes at various levels, coalescing with large
chambers and passages and connected through rising
vertical conduits. Other examples include the Monte Cucco
system in Italy (Figure 24); complex bush-like upwardbranching
structures of hydrothermal caves in the Buda
Hills, Hungary, composed of rising sequences of chambers
and large spherical cupolas (Figure 22, B and C;
Dubljansky Ju, 2000b); and network maze clusters at the
base of the Joachim Dolomite in eastern Missouri, USA,
with ascending staircase limbs of vertical pits and subhorizontal
passages (outlet component; Brod, 1964; Figure
39).
Multi-story mazes are variants of complex 3-D
patterns. In a typical system, lower stories or individual
rising conduits are recharge elements to a cave system.
Master stories develop at intermediate elevations where
there are laterally connected fracture systems. Upper
stories serve as outflow structures (“outflow mazes” of
Ford, 1989). Small patches of maze or lateral extensions of
high cupola structures may develop at higher or highest
elevations without bearing outflow functions
(“adventitious” mazes of Ford), especially in systems
where buoyancy flow plays a role.
In summary, the 3-D structure of hypogenic caves is
controlled mainly by the distribution of initial permeability
structures across the cave formation and adjacent
formations, interaction of different permeability structures
at various levels, and overall recharge/discharge
conditions. Geochemical interaction of flow systems
guided by transverse and lateral permeability pathways
also may play a significant role. Buoyancy effects in free
convection and mixed systems can also be important in
creating complex cave structures.
4.3 The maze caves controversy
The most common (although not the only) pattern for
hypogenic transverse speleogenesis is a network maze.
Network mazes, often with several superimposed stories,
constitute entire caves or parts of complex cave structures.
The formation of maze cave patterns has been
specifically addressed in the karst literature for many
years. Researchers who previously attributed the origin of
maze caves to artesian conditions (e.g. Howard, 1964;
White, 1969; Ford, 1971; Huntoon, 2000) or disregarded
this possibility (Palmer, 1975, 1991, 2000b) implied the
“classical” concept of lateral artesian flow through a
soluble unit. Palmer examined the hydraulic-kinetic
conditions within a simple loop in which water diverges
into two branches that rejoin downstream, and showed that
these branches cannot develop at comparable rates except
at very high discharge to flow length (Q/L) ratios. Such
conditions are not characteristic of lateral artesian flow, so
he concluded that slow groundwater flow near chemical
equilibrium, typical of confined aquifers, is least likely to
produce maze caves (Palmer, 1975; 1991, 2000a).
White (1969) described the type of a “sandwich
aquifer”, where a thin carbonate unit is overlain and
underlain by insoluble strata. He noted that network caves
are characteristic for this situation and pointed out that
such patterns form due to the lack of concentrated recharge
from overlying beds.
Palmer (1975) specifically addressed the problem of
maze patterns and suggested two main settings favorable
for their development:
1) High-discharge or high-gradient flow during floods in
the vicinity of constrictions in the main stream passages
(floodwater mazes) and,
2) Diffuse recharge to a carbonate unit through a
permeable but insoluble caprock such as quartz sandstone.
Figure 17. Profile of Lechuguilla Cave, NM, USA, by National Park Service volunteers, courtesy of US National Park Service. The cave is
currently surveyed at 193.4 km in length and 490 m in depth. This is an example of a complex 3-D structure, in which some prominent inlet
(feeding) and outlet components are easily recognizable.
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